1. Field of the Invention
This invention pertains to nuggets made of wood particles and a resinous binder which are useful as fuel, for example in automated furnaces, and more particularly, to nuggets made from particleboard. The invention also pertains to a method of making the nuggets.
2. Description of the Prior Art
One of the commonly used materials in the building industry and related arts is particleboard. The term particleboard refers to a sheet of material having preselected dimensions and weight, and usually made from a blend of wood particles such as wood shavings, sawdust, plywood trim, etc., which are held together with a urea-formaldehyde binder. A description of how such particleboard is made can be found in U.S. Pat. Nos. 4,186,242 (Holmquist, Jan. 29, 1980) and No. 4,397,756 (Lehmann, Aug. 9, 1983). Because particleboard is frequently used in high visibility areas such as countertops, furniture, and the like, the industry has high quality control standards. Sheets of particleboard which deviate from the standards or exhibit surface irregularities are often scrapped. Particleboard also is relatively fragile, especially around the edges, and breaks easily. In addition, in the manufacture of particleboard there is inherently a certain amount of trim scrap from the molding process and other manufacturing processes. As a result, the manufacturers have quantities of particleboard which cannot be sold to the industry and cannot be recycled in that it is made with thermosetting resin. This material has either been shipped to land fills or incinerated.
One recognized problem with particleboard is that if the board is not sealed, the formaldehyde used in the binder is released to the ambient atmosphere. It has been found that exposure of people to large concentrations of formaldehyde in the atmosphere is undesirable because it can be the cause of health problems. Some of these problems are discussed in U.S. Pat. No. 4,443,354 (Eian, Apr. 17, 1984). Various solutions have been proposed in the past to deal with this problem, however, none of them were found to be acceptable in the industry. For example, the above-mentioned U.S. Pat. No. 4,443,354 proposed an absorbent material for use as a filtration media for absorbing formaldehyde. The above-mentioned U.S. Pat. No. 4,186,242 proposed treating lignocellulosic composites (i.e., the wood chips) with an ammonium-based lignosulfonate. The above-mentioned U.S. Pat. No. 4,397,756 proposed adding a carbohydrate-based material such as cooked or gelatinized starch. U.S. Pat. No. 4,410,685 (Williams, Oct. 18, 1983) proposed a urea-formaldehyde resin as an adhesive which is hydraulically stable whereby free formaldehyde is eliminated.
It is clear from the above that there is a need for a product which can be made of particleboard scrap. More particularly, there is a need for a product which can be made in a manner so as to limit the release of formaldehyde therefrom.